Extension-ladder.



No. 697,294. Patented Apr. 8, I902. C. B. TUTMAN.

EXTENSION LADDER.

(Application filed Dec. 21, 1900.) v

2 Sheets-Sheet I.

(No Model.)

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No. 697,294. Pa tented Apr. 3, I902.

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EXTENSION LADDER.

(Application filed Dec. 21, 1900.) (No Model.) 2 Sheets-Sheet 2;

- ai M UNlTED STATES PATENT V OFFICE.

CHARLES B. TOTMAN, OF MINNEAPOLIS, MINNESOTA.

EXTENSION-LADDER.

SPECIFICATION forming part Of Letters Patent No. 697,294, dated April 8, 1902.

Application filed December 21, 1900. Serial No. 40.702. (No model.) I

T aZZ whom, it may concern.-

Be it known that 1, CHARLES B. TOTMAN, a citizen of the United States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have invented a new and useful Improvementiu Extension-Ladders, of which the following is a specification, reference being had to the accompanying drawings.

My invention relates to a class of ladders which may be extended or lengthened, thus adapting them for use in the fire-department of cities, also by painters, carpenters, roofers, and others using ladders variable in length.

In the accompanying drawings, Figure 1 is a front elevation and top view of one of my improved ladders; Fig. 2, a side elevation and top View of same; Fig. 3, a front elevation and top view of the lower section thereof; Fig. 4, the same of the upper section thereof; Fig. 5, a side elevation of the clamping mechanism detached; Fig. 6, a vertical section of the same; Fig. 7 a horizontal section thereof, and Figs. 8 and 9 details.

Similar letters and numerals refer to similar parts throughout the several views, A being the lower section, B the upper section, 0 the clamping device, and D the operating mechanism.

The lower or stationary section A consists of the two parallel beams 1 and the rungs 2, the former being laterally pierced at regular intervals and the latter having their ends affixed in the former after the manner of forming ladders in general. It is provided at its upper end and intermediate its length with the braces 3, the purpose of which will hereinafter be set forth.

The upper or movable section B is constructed substantially the same as the lower section A, save that the rungs 2 are shorter. Hence this section is not as wide as the lower one.

The clamping mechanism consists of the shaft 4, the jaws 5, the stop 6, and the spring 10. The shaft 4 is the same length as the rungs 2 of the lower section A, in which lower section it is revolubly affixed, having its ends turned down to form journals 4, upon which it rotates. Near its journaled ends 4 are sections 4", havingthereon right and left hand threads-that is to say, a right-hand thread at one journal and a left-hand thread at the other and adjacent thereto reverselythreaded sections 4 thus having both right and left hand threads at each end of the shaft. These reversely-threaded sections 4 are separable from the shaft 4, being reversely-threaded sleeves upon which the reversely-tln'eaded jaws 5 are respectively mounted, after which they are slipped over the ends of the shaft 4, where they are secured by means of pins or rivets. The jaws 5 consist of the hub portions 5 and the face portion 5", the former being interiorly threaded and the latter being fashioned with the locking-notch 5. One pair of these jaws is provided with righthand threads and the other pair with lefthand threads, thereby adapting them to engage the right and left hand threads of the shaft 4. The stops 6 are affixed to the beams 1 of section A, the arms 6 of which interlock with the notches 5 of the jaws 5. This construction permits the jaws 5 to be moved longitudinally of the sleeves when the shaft 4 is rotated, while at the same time it prevents them from rotating with the said sleeves.

The operating mechanism D consists of the lever 7, the rope 8, the pulley 9, the spring 10, the ribbon 11, the spindle 12, the spool 13, the wheel 14, the cable 15, and the cord 16.

The lever 7 is rigidly affixed to the reverselythreaded shaft 4 and stands normally in an upwardly-inclined position, as shown in Fig. 2. It is operated by means of the rope 8, attached thereto and extending downward therefrom. The pulley 9 is rigidly affixed to and rotates with the shaft 4. The ribbon 11 or its mechanical equivalent is affixed to the periphery of the pulley 9 and extends to and is connected with the spring 10. The spindle 12 (like the shaft 4) is revoluble in the beams 1 of the stationary section A. The spool 13 and the sheave-wheel 14 are rigidly affixed to and revoluble with the spindle 12. One end of the cable 15 is affixed to the periphery of the spool 13, winds several times around the same, thence extends downward to and-is affixed to the lower rung of the movable sec tion B. The cord 16 is endless, passing over the wheel 14 and under a similar wheel affixed to one of the lower rungs 1 of the sta-' tionary section A.

The operation of my device is as follows:

The device being placed upright, as shown in Figs. 1 and 2, and it being desirable to extend it, I first pull downward on the rope 8, thereby deflecting the lever 7 and rotating the shaft 4 about one-fourth of a revolution, thus causing thejaws 5,respectively,to recede from their fellows, thus releasing the beams 1 of the movable section B. I now raise the said upper section B by drawing downward on the cord 16, which through the operations of the wheel 14, spindle 12, the spool 13, and the cable 'raises the said upper section B to the required height. I now release the tension upon the rope 8, when the spring 10 through its reflex action will return the shaft 4 to its normal position, which will through the reversely-threaded shaft cause the jaws 5, respectively, to move toward their fellows, thereby again clamping the beams 1 of the upper section B and holding them rigidly at that point. Thus it will be seen that the two sections of my ladder A and B are held clamped at any desired position through the recoil or reflex action of the spring 10 and that the said spring 10 is deflected only while the adjustment ofthe parts (the extension of the ladder) is being made.

I am aware that operating mechanism similar to that shown and described has been used in extension-ladders, and I do not, therefore, claim it, broadly, in this invention; but

What I do claim, and desire to secure by Letters Patent, is

1. In aladder of the character herein shown, the combination with a stationary section and a movable section, of the clamping mechan-' ism, embodying the reversely-threaded shaft 4, revolubly mounted in the beams of the said stationary section; the reverselythreaded jaws 5, mounted upon, and carried by the said reversely-threaded shaft, the stops 6, affixed to the said stationary section and interlocking with the saidreversely-threaded jaws; and the spring 10, one end of which is affixed to the said stationary section, and the other end of which is connected with the said revoluble shaft, which spring, through its reflex action rotates the said reversely threaded shaft thereby causing the jaws adjustably mounted thereon, to respectively approach their fellows, thereby clamping the beams of the said movable section, and means for operating the said clamping mechanism, all sub stantially as shown and described.

2. In a ladder of the character herein shown, the combination with the stationary section, and the movable section thereof; of the clamping mechanism 0, and the operating mechanism D, said clamping mechanism embodyin g a reversely-tllreaded shaft revolubly affixed in the beams of the said stationary section; reversely-threaded jaws mounted thereon and carried thereby, stops affixed to said stationary section and interlocking with the said jaws, and a spring for normally holding the said jaws in contact with the beams of the said movable section; and the said operating mechanism embodying a lever affixed upon the said revoluble shaft; a pulley affixed to and revoluble with the said shaft, a ribbon affixed to the periphery of the said pulley and connected with the spring of the said clamping mechanism, and a rope to depress the said lever and to deflect the said spring, substantially asshown and described.

CHARLES B. TOTMAN.

Witnesses:

E. O. MORSE, W. H. Soo'rT. 

